This invention relates generally to integrated circuit capacitors and methods for making the same and particularly to the variety of devices that include integrated circuit capacitors such as memory cells, logic devices and other semiconductor microelectronic devices.
It is very important in the formation of semiconductor devices to form high quality capacitors. A capacitor basically includes a conductive layer separated from a substrate by a dielectric layer.
In many cases, semiconductor capacitors provide critical functions. For example, in connection with memory devices, a capacitor may be used to erase a floating gate. A floating gate is a conductive layer which may be injected with charge to define a memory state. When it is desired to erase a cell which contains charge, the charge must be induced to flow from the floating gate through a dielectric into a substrate. Particularly in these and other situations where thin dielectrics are utilized, the integrity of the dielectric may be important to the operating characteristics of the resulting device.
Conventional capacitors are made by implanting a substrate with a conductivity type determining impurity. A dielectric layer is then grown over the implanted substrate and a conductive layer is patterned and formed over the dielectric layer. Thus, the dielectric layer may be formed over a substrate which is highly damaged because of ion implantation effects. This may mean that the resulting oxide layer and the adjacent surface of the substrate may be adversely affected by the implant damage. This may adversely affect the operation of the resulting capacitor.
Thus, there is a continuing need for integrated circuit capacitors which have improved quality and characteristics and particularly to those that are useful with relatively thin dielectric layers.